Battery Type and Battery Life


NiMH vs Lithium Ion: Which battery is better for electric toothbrushes?

Rechargeable batteries in electric toothbrushes these days are either NiMH or Lithium-ion cells. What are the differences? Is one better than the other?

This question is important because nearly all powered toothbrushes have build-in batteries, you are not supposed to change. In order to be able to enjoy a long life, it is important to know how to treat your battery and what to avoid.

 NiMHLithium ion
Energy density140 – 300 Wh/L250 – 676 W·h/L
Cycle durability180 – 2000400 – 1200
Pricelowerhigher

Nickel-metal or NiMH Battery

NiMh batteries have a higher energy density compared to nickel–cadmium (NiCd) type . This is the amount of energy it can store in relation to its size. And with toothbrush handles size does matter a lot more than with i.e. a power drill.

All battery types self-discharge over time. That means they use power even when not used. NiMH cells loose loose the most energy the first day after charging. It slows down after that and the amount of power it is loosing over time depends a lot on temperature. Higher temperature means it will discharge faster. Another factor that plays a roll here is age. Older batteries discharge faster than newer ones.

No matter how “full” a NiMH cell is, it is able to power your toothbrush with nearly the same voltage. You will not notice any difference in brushing speed until the battery is almost dead.

When it comes to security, NiMH batteries have very small risk of bursting when overcharged. Overcharging will cause hydrogen gas to build up within the battery. In order to protect the cells from rupturing, the have a safety valve to allow the gas to safely escape.

Depending on the brand a Nickel-metal cell can be charged 180 to 2000 times. When it not longer can hold the charge, it is recyclable. The chemicals used are just mildly toxic which makes the battery kind of environmentally friendly.

The often feared memory effect is negligible if you treat your battery right.. It is true that partial discharge may lead to memory effect. Fortunately it can be treated by charging  and discharging the battery completely a few times. It is not a very practical solution though if you consider  a charging time of around 12 hours some electric toothbrushes require. If you want to do a few cycles you would not be able to use your brush for several days. Lithion-ion cells do not have this problem.

Lithium ion or Li-ion Battery

Lithium ion batteries have a higher energy density than NiMH batteries. Smaller sized batteries allow to build slimmer handles.

Another advantage is the faster charging. There is no need to wait for 12 hours before you can use your new toothbrush.

The self-discharge rate of Lithium-ion cells is much lower than the NiMH kind. Additionally there is no memory-effect. The need to discharge and charge them completely is not necessary to prolong the battery’s life. On the contrary, draining a Lithion-ion battery completely is not advisable. It will ruin it. The build-in computer should that takes care it does not happen.

One disadvantage of this battery type beside the higher price is a slight safety risk. In contrary to other types the electrolyte used is flammable and the whole battery is under pressure. Faulty manufacturing can lead to fires and resulted in recalls in the past. You may have followed the issues Samsung had with their S7 batteries.

A lot of toothbrush owners complain that their toothbrush dies shortly after the warranty of two years end. That is no surprise if you know, that Lithium ion cells age. The average life span is two to three years.



Oral-B Smart Series 6500

The Smart Series 6500 is effectively a glorified Oral-B Pro 6000 with a an additional bonus electric toothbrush handle. Think buy one get one free.

If you need two electric toothbrush handles for the family, the Oral-B Smart Series 6500 is the most economical way to do it and offers great value for money. The electric toothbrush handles themselves are top of the range electric toothbrush handles that offers a great range of features for a cheap price.

Effectively this Oral-B Smart Series 6500 is 2 x Oral-B pro 6000 electric toothbrush handles being sold together at a discounted price.

Oral-B Smart Series 6500 Features

5 Cleaning Modes – The primary reason many people opt to spend a little more for the Smar tSeries 6500 is for the multiple cleaning modes available to suit your needs, and for a more rounded cleaning experience.

  1. Daily Clean is the default mode for regular cleaning.
  2. Pro Clean operates at a higher frequency for more extensive cleaning when needed.
  3. Sensitive is gentler on your teeth to avoid pain, but still allows you to clean your teeth sufficiently.
  4. Whitening allows you to polish your teeth and can be used occasionally or daily.
  5. Gum Care provides a gentle massaging effect on the gums to stimulate blood flow and improve gum health.

Bluetooth Compatibility
Just one of aspects that makes this toothbrush so smart is it’s Bluetooth compatibility. It allows you to connect to the Oral-B app on your smartphone or tablet so you can learn more about your oral cleaning routine and brushing habits, and informs you of ways to improve them. While the app is geared toward the higher end ‘Genius’ line of Oral-B toothbrushes, it can still be helpful in letting you know the battery life, what mode you are in, when you are brushing too hard and more. It also saves data of the last 20 brushes automatically and syncs it when you open the app again.

Smart Wireless Guide

Smart Wireless Guide
In addition to being able to connect to your smartphone, included is a small white, wireless guide that can be placed on a shelf or stuck to a wall. It seamlessly connects to the 6000 brush handle and will let you know how long you have been brushing for, if you apply too much pressure (a sad face will appear), as well as what brushing mode you have selected. This latter point is important as there isn’t a clear indicator on the toothbrush itself and many people may not choose to use the app.

Visible Pressure Sensor LED
One issue that many people have with toothbrushes in general is that they use too much pressure which can cause damage to gums and tooth enamel. The Smart Series 6500 features an easy-to-see LED on the reverse side that flashes in red when too much force is applied as a warning. Additionally, the toothbrush will reduce power temporarily whilst in daily clean, pro clean and sensitive cleaning modes.


QuadPacer
The Smart Series 6500 vibrates every 30 seconds to let you know when to move from one corner of your mouth to the other. While this is a common feature on Oral-B electric toothbrushes, the 6500 also has a green LED indicator that lights up as well to let you know when to change positions, and yellow when the recommended two minutes of brushing is up. This is the same LED that lets you know when you use too much pressure.

Battery Life
The Oral-B Smart Series 6500 uses a Ni-MH (nickel-metal hydride) battery which many won’t be overly pleased with. The reason being is that lithium-ion is so much more effective these days at holding a charge for longer, and without fading. Some of their other higher end series lite Genius toothbrushes use lithium-ion. Having said that, the 6500 still provides around 40 minutes of power on a single charge, which is enough for around 10 days of charging if you don’t keep it on the dock. While this isn’t as much as some of their other models or its competitors, it does a little extra power for the accent lighting and Bluetooth.

One issue with Ni-MH batteries in particular is that its recommended to let the batteries run down before fully charging to maintain the life of the battery. For this reason you may want to consider the Genius 9000 model which is more advanced, and uses lithium-ion.

One Charger
The small white charging dock is the same used by almost all Oral-B electric toothbrushes, though you can also choose to attach it to the included brush head holder. These chargers are very easy to clean with just warm water and a cloth.

Battery and Charging Indicator
The 6000 brush handle has a green three stage battery LED indicator at the bottom which is helpful in letting you know just how much juice is left. When the battery is depleted and needs to be recharged, the light will flash red. It’s worth noting that it’s recommended to charge the toothbrush for around a day before using it, even if though you’ll be tempted to test it right away.

For charging duration and how long per charge last, please read – Charging your electric toothbrush

Replacement Brush heads
As with all the Oral-B Range, the Oral-B Pro 6500 is compatible with all the Oral-B Brush heads . My particular favourite is the Cross action brush head because of the angulation of the bristles and the small size of the brush head.

What’s in the Box?
As one of the more exciting offerings from Oral-B, buyers will be excited to unbox the following after their purchase:

  • 2 x Oral-B Pro 6000 Electric Toothbrush handles
  • 4 x Brush Heads (CrossAction, 3D White, Floss Action and Sensitive Clean)
  • 1 x Charging Station
  • 1 x Brush Head Storage Compartment
  • 1 x Wireless Smart Guide
  • 1 x Travel Case

Battery Type and Battery Life

NiMH vs Lithium Ion: Which battery is better for electric toothbrushes?

Rechargeable batteries in electric toothbrushes these days are either NiMH or Lithium-ion cells. What are the differences? Is one better than the other?

This question is important because nearly all powered toothbrushes have build-in batteries, you are not supposed to change. In order to be able to enjoy a long life, it is important to know how to treat your battery and what to avoid.

 NiMHLithium ion
Energy density140 – 300 Wh/L250 – 676 W·h/L
Cycle durability180 – 2000400 – 1200
Pricelowerhigher

Nickel-metal or NiMH Battery

NiMh batteries have a higher energy density compared to nickel–cadmium (NiCd) type . This is the amount of energy it can store in relation to its size. And with toothbrush handles size does matter a lot more than with i.e. a power drill.

All battery types self-discharge over time. That means they use power even when not used. NiMH cells loose loose the most energy the first day after charging. It slows down after that and the amount of power it is loosing over time depends a lot on temperature. Higher temperature means it will discharge faster. Another factor that plays a roll here is age. Older batteries discharge faster than newer ones.

No matter how “full” a NiMH cell is, it is able to power your toothbrush with nearly the same voltage. You will not notice any difference in brushing speed until the battery is almost dead.

When it comes to security, NiMH batteries have very small risk of bursting when overcharged. Overcharging will cause hydrogen gas to build up within the battery. In order to protect the cells from rupturing, the have a safety valve to allow the gas to safely escape.

Depending on the brand a Nickel-metal cell can be charged 180 to 2000 times. When it not longer can hold the charge, it is recyclable. The chemicals used are just mildly toxic which makes the battery kind of environmentally friendly.

The often feared memory effect is negligible if you treat your battery right.. It is true that partial discharge may lead to memory effect. Fortunately it can be treated by charging  and discharging the battery completely a few times. It is not a very practical solution though if you consider  a charging time of around 12 hours some electric toothbrushes require. If you want to do a few cycles you would not be able to use your brush for several days. Lithion-ion cells do not have this problem.

Lithium ion or Li-ion Battery

Lithium ion batteries have a higher energy density than NiMH batteries. Smaller sized batteries allow to build slimmer handles.

Another advantage is the faster charging. There is no need to wait for 12 hours before you can use your new toothbrush.

The self-discharge rate of Lithium-ion cells is much lower than the NiMH kind. Additionally there is no memory-effect. The need to discharge and charge them completely is not necessary to prolong the battery’s life. On the contrary, draining a Lithion-ion battery completely is not advisable. It will ruin it. The build-in computer should that takes care it does not happen.

One disadvantage of this battery type beside the higher price is a slight safety risk. In contrary to other types the electrolyte used is flammable and the whole battery is under pressure. Faulty manufacturing can lead to fires and resulted in recalls in the past. You may have followed the issues Samsung had with their S7 batteries.

A lot of toothbrush owners complain that their toothbrush dies shortly after the warranty of two years end. That is no surprise if you know, that Lithium ion cells age. The average life span is two to three years.

Oral-B’s rated battery usage life

While Oral-B rated their toothbrush battery usage life by number of days, based on brushing twice a day and 2 minutes per session. i.e. if the rated number of days is 7 days, that would mean the battery life is basically 7 x 2 x 2 = 28 minutes.

Please note that excessive pressure during cleaning or usage that lasts longer than 2 minutes during the session can reduce the rated battery life, as more battery is consumed.